Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1996-10-28
2001-03-20
Vu, Huy D. (Department: 2733)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S328000
Reexamination Certificate
active
06205143
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to asynchronous transfer mode (ATM) networks and, in particular, to variable bandwidth access to an ATM network for wireline and wireless communications.
2. Description of Related Art
Broadband transmission and switching have become important topics in the communications industry. A new system has been implemented for transmitting broadband and narrowband packet and circuit signals over a broadband network. This system is commonly referred to as asynchronous transfer mode (ATM). In ATM, data is packed into frames, with each frame segmented into a plurality of fixed length blocks called “cells.” Each ATM cell is fifty-three bytes (or octets) long and consists of a five byte header indicating, as one of its functions, the destination of the cell, followed by a forty-eight byte payload containing the data to be transmitted to that destination.
The use of ATM cells permits the information transfer rate over the physical medium of the broadband network to adapt to actual service requirements. Depending on the capacity required, the number of cells per unit of time may be increased in a variable bit rate (VBR) ATM network up to the transmission bit rate limit of the physical medium. Alternatively, constant bit rates (CBR) are supported, with the transmission bit rate adjusted by the inclusion of idle or fill in cells when necessary. The cells are transported over the physical medium at a typical constant bit rate of, for example, 155.52 Mbits per second. Faster bit rates are supported for communications occurring solely within the ATM network.
One important characteristic of ATM technology relates to its protocol architecture and is built around the so-called “core-and-edge” principle. The protocol functions specific to the information type being transported, such as retransmissions, flow control, and delay equalization, are performed in user terminals at the “edges” of the ATM network. This leaves an efficient, service-independent “core” network, including only simple cell-transport and switching functions. A user-to-network interface (UNI) implementing an ATM adaptation layer (AAL) is provided at the “edge” of the network to connect the user terminals to the core network thereby allowing for service-independent ATM transport. The ATM adaptation layer performs a mapping operation between the bit stream data format of the user terminals external to the ATM network and the payload field of an ATM cell transmitted through the network.
A number of different bit stream data formats are known and used external to the ATM network. Most of these formats are user specific in that they support and accommodate only the data in the format and rate transmitted to or from user terminals. For example, in the telecommunications art, separate bit stream data formats are known for packet voice and pulse code modulated (PCM) signals. Furthermore, high quality video and data (file transfer) applications have still further different bit stream data formats. There would be a distinct advantage to having a single bit stream format capable of supporting variable bandwidth ATM network access with respect to a plurality of different user terminals and their associated data formats. Such a bit stream would preferably be flexible enough to convey packet and PCM voice, data and/or packet video, and further provide built-in capabilities for operation and maintenance and add/drop multiplexing.
SUMMARY OF THE INVENTION
The present invention comprises a communications system using a multi-level data bit stream capable of supporting variable bandwidth ATM network access. The bit stream is dynamic in nature in that it is capable of supporting a number of different sub-rates with respect to its included channel bearers. To support repairability and configurability, the bit stream includes an embedded operation channel used for transmitting operation and maintenance messages. Furthermore, to specify the use of the right amount of bandwidth at the proper location within the communications system, the bit stream includes delimiting data for performing add/drop multiplexing.
In particular, the multi-level data bit stream comprises a basic bit stream block including an appropriate repetition rate for the information being transmitted. The transmission bit rate of the basic bit stream block is a fraction of the transmission bit rate limit of the physical medium used in the ATM network. In instances where higher transmission bit rates are needed, for example in carrying video or data (file transfers), multiple basic bit stream blocks are used to carry the data during the same time period. The basic bit stream block further supports sub-rates useful in carrying voice and data communications in a plurality of channels. With respect to such sub-rate communications, delimiting data is added for performing add/drop multiplexing of the included channels. Furthermore, each basic bit stream block includes an embedded operation channel useful for connection maintenance, performance monitoring, path tracing, supervision and service management functions.
The multi-level data bit stream is used to carry information outside of the ATM network, but is compatible therewith to provide for network access. The present invention accordingly further comprises an interface with the ATM network that is provided through an ATM adaptation layer (AAL) within an ATM access node having a user-to-network interface (UNI) located at the “edge” of the network. The user-to-network interface segments the multi-level data bit stream into forty-six byte parts, plus two bytes for handling AAL #
1
functionality, for insertion into the forty-eight byte payload portion of a plurality of ATM cells. Any destination information for the multi-level data bit stream is formatted within the five byte header portion of each of the ATM cells. On the other side of the ATM network, at the location identified by the translated destination information located within the header portion, the forty-six byte information segments in the ATM payload portion are extracted from the received ATM cells and reassembled to construct the multi-level data bit stream for delivery to the intended destination node.
The present invention further comprises a wireless communications system wherein a base station concentrator is connected through an access node to a ATM network. The concentrator is further connected to a plurality of base stations which effectuate radio frequency communications with a plurality of mobile stations using a plurality of voice channels. Communications over the link connecting the base station concentrator to the access node utilize the foregoing multi-level data bit stream. By means of the embedded operation channel, a transport network management system may perform connection maintenance, performance monitoring, path tracing and testing over the ATM network and with respect to the access node and base station concentrator. The included delimiting bits are used to control the add/drop multiplexing of the wireless communications voice channels.
The present invention still further comprises a wireline communications system wherein a wireline concentrator is connected through an access node to a ATM network. The concentrator is further connected to a plurality of wireline telephone terminals through which subscribers engage in telephone communications using a plurality of voice channels. Communications over the link connecting the wireline concentrator to the access node utilize the foregoing multi-level data bit stream. By means of the embedded operation channel, a transport network management system may perform connection maintenance, performance monitoring, path tracing and testing over the ATM network and with respect to the access node and wireline concentrator. The included delimiting bits are used to control the add/drop multiplexing of the wireline communications voice channels.
With respect to either or a combination of both wireless and wireline communications
Jenkens & Gilchrist P.C.
Telefonaktiebolaget L M Ericsson
Vu Huy D.
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